我正在尝试按照此处的示例创建一个Android语音识别服务：
Android Speech Recognition Continuous Service
以下是我的代码：
public class MainActivity extends Activity {
private int mBindFlag;
Messenger mServiceMessenger;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Context activityContext = getApplicationContext();
Intent service = new Intent(activityContext, VoiceCommandService.class);
activityContext.startService(service);
mBindFlag = Build.VERSION.SDK_INT < Build.VERSION_CODES.ICE_CREAM_SANDWICH ? 0 : Context.BIND_ABOVE_CLIENT;
}
private final ServiceConnection mServiceConnection = new ServiceConnection()
{
@Override
public void onServiceConnected(ComponentName name, IBinder service)
{
//if (DEBUG) {Log.d(TAG, "onServiceConnected");} //$NON-NLS-1$
mServiceMessenger = new Messenger(service);
Message msg = new Message();
msg.what = VoiceCommandService.MSG_RECOGNIZER_START_LISTENING;
VoiceCommandService voiceCommandService = new VoiceCommandService();
try
{
voiceCommandService.mServerMessenger.send(msg);
}
catch (RemoteException e)
{
e.printStackTrace();
}
}
@Override
public void onServiceDisconnected(ComponentName name)
{
//if (DEBUG) {Log.d(TAG, "onServiceDisconnected");} //$NON-NLS-1$
mServiceMessenger = null;
}
};
@Override
protected void onStart()
{
super.onStart();
bindService(new Intent(this, VoiceCommandService.class), mServiceConnection, mBindFlag);
}
public class VoiceCommandService extends Service
{
protected AudioManager mAudioManager;
protected SpeechRecognizer mSpeechRecognizer;
protected Intent mSpeechRecognizerIntent;
protected final Messenger mServerMessenger = new Messenger(new IncomingHandler(this));
protected boolean mIsListening;
protected volatile boolean mIsCountDownOn;
static final int MSG_RECOGNIZER_START_LISTENING = 1;
static final int MSG_RECOGNIZER_CANCEL = 2;
@Override
public void onCreate()
{
super.onCreate();
mAudioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
mSpeechRecognizer = SpeechRecognizer.createSpeechRecognizer(this);
mSpeechRecognizer.setRecognitionListener(new SpeechRecognitionListener());
mSpeechRecognizerIntent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
mSpeechRecognizerIntent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,
RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
mSpeechRecognizerIntent.putExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE,
this.getPackageName());
}
protected class IncomingHandler extends Handler
{
private WeakReference<VoiceCommandService> mtarget;
IncomingHandler(VoiceCommandService target)
{
mtarget = new WeakReference<VoiceCommandService>(target);
}
@Override
public void handleMessage(Message msg)
{
final VoiceCommandService target = mtarget.get();
switch (msg.what)
{
case MSG_RECOGNIZER_START_LISTENING:
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN)
{
// turn off beep sound
target.mAudioManager.setStreamMute(AudioManager.STREAM_SYSTEM, false);
}
if (!target.mIsListening)
{
target.mSpeechRecognizer.startListening(target.mSpeechRecognizerIntent);
target.mIsListening = true;
//Log.d(TAG, "message start listening"); //$NON-NLS-1$
}
break;
case MSG_RECOGNIZER_CANCEL:
target.mSpeechRecognizer.cancel();
target.mIsListening = false;
//Log.d(TAG, "message canceled recognizer"); //$NON-NLS-1$
break;
}
}
}
// Count down timer for Jelly Bean work around
protected CountDownTimer mNoSpeechCountDown = new CountDownTimer(5000, 5000)
{
@Override
public void onTick(long millisUntilFinished)
{
// TODO Auto-generated method stub
}
@Override
public void onFinish()
{
mIsCountDownOn = false;
Message message = Message.obtain(null, MSG_RECOGNIZER_CANCEL);
try
{
mServerMessenger.send(message);
message = Message.obtain(null, MSG_RECOGNIZER_START_LISTENING);
mServerMessenger.send(message);
}
catch (RemoteException e)
{
}
}
};
@Override
public void onDestroy()
{
super.onDestroy();
if (mIsCountDownOn)
{
mNoSpeechCountDown.cancel();
}
if (mSpeechRecognizer != null)
{
mSpeechRecognizer.destroy();
}
}
protected class SpeechRecognitionListener implements RecognitionListener
{
private static final String TAG = "SpeechRecognitionListener";
@Override
public void onBeginningOfSpeech()
{
// speech input will be processed, so there is no need for count down anymore
if (mIsCountDownOn)
{
mIsCountDownOn = false;
mNoSpeechCountDown.cancel();
}
//Log.d(TAG, "onBeginingOfSpeech"); //$NON-NLS-1$
}
@Override
public void onBufferReceived(byte[] buffer)
{
}
@Override
public void onEndOfSpeech()
{
//Log.d(TAG, "onEndOfSpeech"); //$NON-NLS-1$
}
@Override
public void onError(int error)
{
if (mIsCountDownOn)
{
mIsCountDownOn = false;
mNoSpeechCountDown.cancel();
}
mIsListening = false;
Message message = Message.obtain(null, MSG_RECOGNIZER_START_LISTENING);
try
{
mServerMessenger.send(message);
}
catch (RemoteException e)
{
}
//Log.d(TAG, "error = " + error); //$NON-NLS-1$
}
@Override
public void onEvent(int eventType, Bundle params)
{
}
@Override
public void onPartialResults(Bundle partialResults)
{
}
@Override
public void onReadyForSpeech(Bundle params)
{
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN)
{
mIsCountDownOn = true;
mNoSpeechCountDown.start();
mAudioManager.setStreamMute(AudioManager.STREAM_SYSTEM, false);
}
//Log.d(TAG, "onReadyForSpeech"); //$NON-NLS-1$
}
@Override
public void onResults(Bundle results)
{
//Log.d(TAG, "onResults"); //$NON-NLS-1$
Toast.makeText(getApplicationContext(), "this is my Toast message!!! =)",
Toast.LENGTH_LONG).show();
}
@Override
public void onRmsChanged(float rmsdB)
{
}
}
@Override
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
return mServerMessenger.getBinder();
}
}
}
有人可以帮助我找出为什么遇到mTarget.AudioManager和mTarget.SpeechRecognitionIntent的nullpointer异常？我也看到我的服务OnCreate方法没有被击中。请告诉我正确的做法？
update - 我试图在BindService方法中调用服务，但是我的服务中的Oncreate方法没有被调用。请指出遗失的内容？
答案 0 :(得分：1)
VoiceCommandService voiceCommandService = new VoiceCommandService()
不要使用new实例化服务 - 生命周期方法（例如onCreate()）不会被调用。
使用Intent。